I thought his observation at the end during the Q & A session about how variability makes predicting small project schedules tough. Example of 50% of Scrum projects missing Sprint feature targets. Also the example of estimates where the high percentage of dark matter (unpredictable issues) introduced problems with trust because padding to account for reality was too large compared to the known estimate. How do you say something will take 9 months when you can only document 3 months worth of tasks.

His comments earlier in the presentation about the importance of rhythm and predictability with end users was right on in my experience. And his point that you build credibility for those times when you miss a deadline is also invaluable to understand.